Class 12 Full Syllabus MCQ Test – Free Practice
Class 12 Full MCQ Test – Online Practice — Practice Questions
1. Which part of the ovule develops into the seed coat after fertilization?
- (A) Nucellus
- (B) Integuments
- (C) Ovary wall
- (D) Endosperm
Answer: (B) Integuments
Integuments develop into the seed coat.
2. Which hormone maintains pregnancy by preparing the uterus for implantation?
- (A) FSH
- (B) LH
- (C) Progesterone
- (D) Oxytocin
Answer: (C) Progesterone
Progesterone maintains the endometrium during pregnancy.
3. The lac operon is induced in the presence of:
- (A) Glucose
- (B) Lactose
- (C) Maltose
- (D) Fructose
Answer: (B) Lactose
Lactose acts as an inducer by inactivating the repressor.
4. Which of the following diseases is caused by Plasmodium?
- (A) Typhoid
- (B) Tuberculosis
- (C) Malaria
- (D) Dengue
Answer: (C) Malaria
Malaria is caused by Plasmodium species.
5. Which scientist proposed the theory of natural selection?
- (A) Lamarck
- (B) Mendel
- (C) Darwin
- (D) Morgan
Answer: (C) Darwin
Charles Darwin proposed natural selection.
6. The bacterium used for producing Bt toxin naturally is:
- (A) Rhizobium
- (B) Bacillus thuringiensis
- (C) Lactobacillus
- (D) Azotobacter
Answer: (B) Bacillus thuringiensis
Bt toxin is produced by Bacillus thuringiensis.
7. Which ecosystem has the highest net primary productivity?
- (A) Desert
- (B) Tundra
- (C) Tropical rainforest
- (D) Grassland
Answer: (C) Tropical rainforest
Tropical rainforests have the highest productivity.
8. Ozone depletion is mainly caused by:
- (A) CO₂
- (B) SO₂
- (C) CFCs
- (D) NO₂
Answer: (C) CFCs
Chlorofluorocarbons destroy ozone.
9. Which level of biodiversity refers to variation within a species?
- (A) Species diversity
- (B) Genetic diversity
- (C) Ecosystem diversity
- (D) Community diversity
Answer: (B) Genetic diversity
Genetic diversity exists within a species.
10. Which solution shows a positive deviation from Raoult's law?
- (A) Acetone + Chloroform
- (B) Benzene + Toluene
- (C) Ethanol + Water
- (D) Ethanol + Acetone
Answer: (D) Ethanol + Acetone
Weaker intermolecular forces cause positive deviation.
11. The electrode potential of the standard hydrogen electrode is:
- (A) +1.0 V
- (B) −1.0 V
- (C) 0.0 V
- (D) +0.5 V
Answer: (C) 0.0 V
SHE is assigned zero potential.
12. Which transition metal ion is colourless?
- (A) Ti³⁺
- (B) Cu²⁺
- (C) Zn²⁺
- (D) Fe³⁺
Answer: (C) Zn²⁺
Zn²⁺ has completely filled d-orbitals.
13. Which complex shows optical isomerism?
- (A) [Co(en)₃]³⁺
- (B) [Ni(CO)₄]
- (C) [PtCl₄]²⁻
- (D) [Cu(NH₃)₄]²⁺
Answer: (A) [Co(en)₃]³⁺
Tris(ethylenediamine)cobalt(III) exhibits optical isomerism.
14. Which compound gives Cannizzaro reaction?
- (A) Ethanal
- (B) Acetaldehyde
- (C) Benzaldehyde
- (D) Propanal
Answer: (C) Benzaldehyde
Aldehydes without α-hydrogen undergo Cannizzaro reaction.
15. Hinsberg reagent is used to distinguish:
- (A) Alcohols
- (B) Phenols
- (C) Amines
- (D) Aldehydes
Answer: (C) Amines
Hinsberg test distinguishes primary, secondary and tertiary amines.